This application claims the priority of German patent document 100 01 062.8, filed Jan. 13, 2000, the disclosure of which is expressly incorporated by reference herein.
The present invention is directed to a motor control method and apparatus for an internal combustion engine.
A controller of this generic type is described in German patent document DE 196 27 280 A1. Its function is to control both fuel injection and ignition for each cylinder by generating a pulsed control signal. In crank angle synchronous combustion cycles, control data sets are generated in the controller taking into account the load at the internal combustion engine: injection time increases with an increase in the load, generating a larger motor torque, and decreases with a reduction in the load. The generated control signals are supplied to those actuators and components that adjust ignition and injection of each cylinder. The various cylinders of the internal combustion engine are supplied in successive cycles with the control data sets for injection and ignition.
In this context, the problem can arise that with high loads or greatly increasing loads, injection time increases to such an extent that, within one working cycle of the internal combustion engine, the time period available for data transmission and injection of fuel into a cylinder is insufficient. As a result, injection time must be limited to a value which is smaller than the theoretical optimum. An increase of the time period for injection to the target value can only be achieved in a later transmission cycle; this, however, results in delayed power build-up which the driver perceives as a poor response characteristic of the internal combustion engine. In idle running for instance, the power build-up of the internal combustion engine reacting to the load increase with a delay can result in xe2x80x9cstallingxe2x80x9d the engine if a load increase suddenly occurs, since the engine cannot respond quickly enough to the load demand.
One object of the invention is to improve the response characteristic of internal combustion engines in the event of load changes.
This and other objects and advantages are achieved by the motor control method and apparatus according to the invention, which provides that in every new transmission cycle a control data set containing both control information for injection of the cylinder currently to be addressed, and reserve information for injection of the cylinder to be addressed in the following cycle is generated in the motor controller. During every transmission cycle, the control data set generated in the motor controller is transmitted to the actuators of the corresponding cylinder which carry out the injection, or to a valve control unit controlling these actuators.
The twofold transmission of control informationxe2x80x94for the cylinder that is currently addressed and for the following cylinderxe2x80x94has the advantage that during every transmission cycle, control information for two successive cylinders is provided; this offers the possibility, particularly in case of a load increase, that the subsequent cylinder can fall back on the reserve information that is generated and transmitted in the previous transmission cycle for controlling the injection. This technique ensures that in the event of a load increase accompanied by a longer injection period per transmission cycle, a longer time period is available for injection because the cylinder can fall back on reserve information transmitted and saved in the previous cycle, if necessary, so that the window of time available for injection for the corresponding (following) cylinder is enlarged. As a result, in the event of a load increase, control information originating from the directly preceding cycle is immediately available. This reduces the time needed for adjusting to the current load to a minimum and significantly improves the response characteristic of the internal combustion engine.
If the internal combustion engine runs in a stable mode, however, with a load that remains essentially constant, the cylinders currently to be addressed are provided with current control information. Reserve information that is generated and transmitted at the same time is saved without being actually used in stable running mode, since it is intended exclusively to define injection data of the subsequent cylinder in the event of a load increase with a greatly increasing injection period.
In accordance with a useful further development, the procedure provides that in the event of a load increase, the cylinder to be addressed currently receives reserve information from the previous transmission cycle; simultaneously, a new set of control data is generated by the motor controller that contains control information for the next following cylinder and reserve information for the next to next cylinder. This procedure ensures that, synchronous with the fixed crank angle, a control data set is generated and transmitted, the control information contained in the control data set being a function of the load. For changes towards higher loads and correspondingly longer injection time periods, two successive control data sets contain control information for a total of four successive cylinders; in this case, distribution logic ensures that the first cylinder is first provided with current control information of the first control data set; that the following cylinder is provided with reserve information of the first control data set; that the subsequent cylinder is then provided with the current control information of the second control data set; and that finally, the cylinder following thereafter is provided with reserve information of the second control data set. Thus it is ensured that each cylinder is provided with information for any type of load situation.
In particular, the data sets contain cylinder specific information regarding lambda control, cylinder deactivation, electronic spark control, etc.
In a stable running mode, during which a sufficiently long time period is available in every transmission cycle for generation and transmission as well as for injection into a current cylinder, two successive control data sets contain control information for a total of three successive cylinders. First, the first cylinder is provided with current control information of the first control data set while reserve information is saved. In the following cycle, the following cylinder is provided with current control information of the second control data set while reserve information of the second control data set intended for the next to next cylinder is stored in a memory unit and overwrites the reserve information from the previous control data set.
For a load reduction, if the start of fuel injection into the current cylinder falls into a later transmission cycle due to the decreased injection period, control information and reserve information that are essentially constant in successive control data sets are transmitted to the cylinder currently to be addressed in at least two successive transmission cycles, thus constituting an advantage. The control data set that is newly generated in every transmission cycle remains essentially constant over at least two successive transmission cycles until the moment for injecting fuel into the cylinder currently to be addressed falls into the transmission cycle of the control data set. This procedure ensures that, even in the event of a significant load decrease accompanied by a significant reduction of the injection period, the cylinder currently to be addressed is provided with control information assigned to this cylinder.
In accordance with the invention, the motor control device includes a motor controller in which, in a load-controlled way, control data sets are generated with control information and reserve information. It also includes at least one valve control unit communicating with the motor controller to which a memory unit is assigned in which reserve information from the control data set can be saved for at least one transmission cycle. In stable running mode, the current control information from the control data set is provided to the actuators for the cylinder currently to be addressed; the reserve information transmitted with the current control data set is stored in the memory unit of the valve control unit, whereby the reserve information from the current transmission cycle overwrites information from the previous cycle. In the event of a load increase, however, the cylinder currently to be addressed is not provided with current control information but with reserve information from the previous transmission cycle.
Both the procedure in accordance with the invention and the control device in accordance with the invention are suited for use with variably adjustable gas shuttle valves, particularly electro-magnetically operable gas shuttle valves, for which the opening moment can purposely be varied as a function of the injection period. Air supply, injection values and advantageously also ignition data are preferably controlled by means of the valve control unit to ensure that all control data are generated and transmitted consistently.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.